Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, China.
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
Sci Total Environ. 2021 Mar 1;758:143682. doi: 10.1016/j.scitotenv.2020.143682. Epub 2020 Nov 24.
The flow regime and biogeochemical cycles are greatly affected by river damming and drought, especially in ephemeral rivers. However, the combined effects have been rarely considered. This study, taking the Dagu River in Jiaodong Peninsula of North China as an example, investigated the dynamic changes in water cycle related to river damming and drought using stable water isotopes for the period 2018-2019. The results indicated that river water isotopes significantly varied temporally and spatially. The temporal variations in river water isotopes appeared to be linked with those in precipitation, but the relationship between river water and precipitation isotopes was greatly affected by river damming, river water-groundwater exchange and potential water pollution. Spatially, a single dam exhibited no significant effect on river water isotopes, but the accumulative impacts of cascade dams resulted in the enrichment of heavy isotopes in river water towards the downstream through increasing hydraulic residence time and water evaporation largely. The inter-annual variations in river water isotopes with increased evaporative fractionation were highlighted by their strong response to the drought in 2019. The combined effects of cascade dams and drought greatly changed water cycle dynamics and further exacerbated water shortage, which should thus be fully considered for water resource management, especially for regions with water-limited but heavily-regulated rivers.
河流筑坝和干旱对水流状态和生物地球化学循环有很大影响，尤其是在短暂河流中。然而，这些联合效应很少被考虑到。本研究以中国华北胶东半岛大沽河为例，使用稳定同位素调查了 2018-2019 年期间与河流筑坝和干旱相关的水循环动态变化。结果表明，河水同位素在时间和空间上都发生了显著变化。河水同位素的时间变化似乎与降水有关，但河水与降水同位素之间的关系受到河流筑坝、河水与地下水交换以及潜在水污染的严重影响。从空间上看，单个水坝对河水同位素没有显著影响，但梯级水坝的累积影响通过大幅增加水力停留时间和水蒸发，导致河水向下游重同位素富集。2019 年干旱时，河水同位素的年际变化因蒸发分馏增加而突显，其强烈响应表明，梯级水坝和干旱的联合效应极大地改变了水循环动态，进一步加剧了水资源短缺，因此应充分考虑到这一点，以进行水资源管理，特别是在水资源有限但受到严格管制的河流地区。
